scholarly journals All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids

2015 ◽  
Vol 11 (8) ◽  
pp. 20150564 ◽  
Author(s):  
Victoria E. McCoy ◽  
James C. Lamsdell ◽  
Markus Poschmann ◽  
Ross P. Anderson ◽  
Derek E. G. Briggs
Keyword(s):  
Visual System ◽  
Sister Taxon ◽  
Characteristic Morphology ◽  
Visual Systems ◽  
Top Predators ◽  
Representative Species ◽  
Ecological Roles ◽  
High Level ◽  
Predatory Arthropods

Pterygotid eurypterids have traditionally been interpreted as active, high-level, visual predators; however, recent studies of the visual system and cheliceral morphology of the pterygotid Acutiramus contradict this interpretation. Here, we report similar analyses of the pterygotids Erettopterus, Jaekelopterus and Pterygotus , and the pterygotid sister taxon Slimonia . Representative species of all these genera have more acute vision than A. cummingsi . The visual systems of Jaekelopterus rhenaniae and Pterygotus anglicus are comparable to that of modern predatory arthropods. All species of Jaekelopterus and Pterygotus have robust crushing chelicerae, morphologically distinct from the weaker slicing chelicerae of Acutiramus . Vision in Erettopterus osiliensis and Slimonia acuminata is more acute than in Acutiramus cummingsi , but not to the same degree as in modern active predators, and the morphology of the chelicerae in these genera suggests a grasping function. The pterygotids evolved with a shift in ecology from generalized feeder to specialized predator. Pterygotid eurypterids share a characteristic morphology but, although some were top predators, their ecology differs radically between genera.

scholarly journals Vision as oculomotor reward: cognitive contributions to the dynamic control of saccadic eye movements

2021 ◽  
Author(s):  
Christian Wolf ◽  
Markus Lappe
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Visual System ◽  
Dynamic Control ◽  
Saccadic Eye Movements ◽  
Saccade Target ◽  
Cognitive Mechanisms ◽  
Foveal Vision ◽  
Subsequent Behavior ◽  
High Level

AbstractHumans and other primates are equipped with a foveated visual system. As a consequence, we reorient our fovea to objects and targets in the visual field that are conspicuous or that we consider relevant or worth looking at. These reorientations are achieved by means of saccadic eye movements. Where we saccade to depends on various low-level factors such as a targets’ luminance but also crucially on high-level factors like the expected reward or a targets’ relevance for perception and subsequent behavior. Here, we review recent findings how the control of saccadic eye movements is influenced by higher-level cognitive processes. We first describe the pathways by which cognitive contributions can influence the neural oculomotor circuit. Second, we summarize what saccade parameters reveal about cognitive mechanisms, particularly saccade latencies, saccade kinematics and changes in saccade gain. Finally, we review findings on what renders a saccade target valuable, as reflected in oculomotor behavior. We emphasize that foveal vision of the target after the saccade can constitute an internal reward for the visual system and that this is reflected in oculomotor dynamics that serve to quickly and accurately provide detailed foveal vision of relevant targets in the visual field.

scholarly journals Visual search for object categories is predicted by the representational architecture of high-level visual cortex

2017 ◽  
Vol 117 (1) ◽  
pp. 388-402 ◽  
Author(s):  
Michael A. Cohen ◽  
George A. Alvarez ◽  
Ken Nakayama ◽  
Talia Konkle
Keyword(s):  
Visual Cortex ◽  
Visual Search ◽  
Visual System ◽  
Visual Processing ◽  
Search Task ◽  
Visual Search Task ◽  
Visual Object ◽  
Neural Responses ◽  
Object Categories ◽  
High Level

Visual search is a ubiquitous visual behavior, and efficient search is essential for survival. Different cognitive models have explained the speed and accuracy of search based either on the dynamics of attention or on similarity of item representations. Here, we examined the extent to which performance on a visual search task can be predicted from the stable representational architecture of the visual system, independent of attentional dynamics. Participants performed a visual search task with 28 conditions reflecting different pairs of categories (e.g., searching for a face among cars, body among hammers, etc.). The time it took participants to find the target item varied as a function of category combination. In a separate group of participants, we measured the neural responses to these object categories when items were presented in isolation. Using representational similarity analysis, we then examined whether the similarity of neural responses across different subdivisions of the visual system had the requisite structure needed to predict visual search performance. Overall, we found strong brain/behavior correlations across most of the higher-level visual system, including both the ventral and dorsal pathways when considering both macroscale sectors as well as smaller mesoscale regions. These results suggest that visual search for real-world object categories is well predicted by the stable, task-independent architecture of the visual system. NEW & NOTEWORTHY Here, we ask which neural regions have neural response patterns that correlate with behavioral performance in a visual processing task. We found that the representational structure across all of high-level visual cortex has the requisite structure to predict behavior. Furthermore, when directly comparing different neural regions, we found that they all had highly similar category-level representational structures. These results point to a ubiquitous and uniform representational structure in high-level visual cortex underlying visual object processing.

Visual Systems and the Role of Vision in Subterranean Rodents: Diversity of Retinal Properties and Visual System Designs

2007 ◽  
pp. 129-160 ◽  
Author(s):  
Pavel Němec ◽  
Pavla Cveková ◽  
Hynek Burda ◽  
Oldřich Benada ◽  
Leo Peichl
Keyword(s):  
Visual System ◽  
Subterranean Rodents ◽  
Visual Systems ◽  
System Designs

The Insect Visual System: Correspondence with Vertebrates and with Olfactory Processing

2017 ◽  
pp. 293-306
Author(s):  
Nicholas J. Strausfeld
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Nobel Prize ◽  
Insect Visual System ◽  
Dendritic Trees ◽  
Optic Lobes ◽  
Visual Systems ◽  
Valid Comparison ◽  
Olfactory Processing ◽  
Lateral Protocerebrum

A 1915 monograph by the Nobel Prize–winning neuroanatomist Santiago Ramón y Cajal and Domingo Sánchez y Sánchez, describing neurons and their organization in the optic lobes of insects, is now standard fare for those studying the microcircuitry of the insect visual system. The work contains prescient assumptions about possible functional arrangements, such as lateral interactions, centrifugal pathways, and the convergence of neurons onto wider dendritic trees, to provide central integration of information processed at peripheral levels of the system. This chapter will consider further indications of correspondence between the insect-crustacean and the vertebrate visual systems, with particular reference to the deep organization of the optic lobe’s third optic neuropil, the lobula, and part of the lateral forebrain (protocerebrum) that receives inputs from it. Together, the lobula and lateral protocerebrum suggest valid comparison with the visual cortex and olfactory centers.

AWAVS, a Research Facility for Defining Flight Trainer Visual System Requirements

1978 ◽  
Vol 22 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Stanley C. Collyer ◽  
Walter S. Chambers
Keyword(s):  
Visual System ◽  
Wide Angle ◽  
Experimental Facility ◽  
Research Facility ◽  
Pilot Performance ◽  
System Parameters ◽  
Systems Research ◽  
Visual Systems ◽  
System Requirements ◽  
And Training

The objective of the Navy's Aviation Wide Angle Visual System (AWAVS) program is to recommend design criteria for future flight simulator visual systems. Research leading to this goal will have two facets: improving visual system technology, and determining the effects of visual system parameters on pilot performance and training. The experimental facility is described, and the behavioral research plans are discussed, with emphasis on the carrier landing studies to be conducted during the first phase of the program.

scholarly journals The visual ecology of Holocentridae, a nocturnal coral reef fish family with a deep-sea-like multibank retina

2020 ◽  
pp. jeb.233098
Author(s):  
Fanny de Busserolles ◽  
Fabio Cortesi ◽  
Lily Fogg ◽  
Sara M. Stieb ◽  
Martin Luehrmann ◽  
...  
Keyword(s):  
Visual System ◽  
Reef Fish ◽  
Deep Sea ◽  
Colour Vision ◽  
Ganglion Cells ◽  
Light Sensitivity ◽  
Fish Family ◽  
Visual Systems ◽  
Retinal Topography ◽  
Dim Light

The visual systems of teleost fishes usually match their habitats and lifestyles. Since coral reefs are bright and colourful environments, the visual systems of their diurnal inhabitants have been more extensively studied than those of nocturnal species. In order to fill this knowledge gap, we conducted a detailed investigation of the visual system of the nocturnal reef fish family Holocentridae. Results showed that the visual system of holocentrids is well adapted to their nocturnal lifestyle with a rod-dominated retina. Surprisingly, rods in all species were arranged into 6-17 well-defined banks, a feature most commonly found in deep-sea fishes, that may increase the light sensitivity of the eye and/or allow colour discrimination in dim-light. Holocentrids also have the potential for dichromatic colour vision during the day with the presence of at least two spectrally different cone types: single cones expressing the blue-sensitive SWS2A gene, and double cones expressing one or two green-sensitive RH2 genes. Some differences were observed between the two subfamilies, with Holocentrinae (squirrelfish) having a slightly more developed photopic visual system than Myripristinae (soldierfish). Moreover, retinal topography of both ganglion cells and cone photoreceptors showed specific patterns for each cell type, likely highlighting different visual demands at different times of the day, such as feeding. Overall, their well-developed scotopic visual systems and the ease of catching and maintaining holocentrids in aquaria, make them ideal models to investigate teleost dim-light vision and more particularly shed light on the function of the multibank retina and its potential for dim-light colour vision.

scholarly journals Why are “What” and “Where” Processed by Separate Cortical Visual Systems? A Computational Investigation

1989 ◽  
Vol 1 (2) ◽  
pp. 171-186 ◽  
Author(s):  
Jay G. Rueckl ◽  
Kyle R. Cave ◽  
Stephen M. Kosslyn
Keyword(s):  
Visual System ◽  
Spatial Information ◽  
Systems Design ◽  
Computational Investigation ◽  
Connectionist Models ◽  
Internal Representations ◽  
Visual Systems ◽  
Computational Resources ◽  
Computational Properties ◽  
Hidden Nodes

In the primate visual system, the identification of objects and the processing of spatial information are accomplished by different cortical pathways. The computational properties of this “two-systems” design were explored by constructing simplifying connectionist models. The models were designed to simultaneously classify and locate shapes that could appear in multiple positions in a matrix, and the ease of forming representations of the two kinds of information was measured. Some networks were designed so that all hidden nodes projected to all output nodes, whereas others had the hidden nodes split into two groups, with some projecting to the output nodes that registered shape identity and the remainder projecting to the output nodes that registered location. The simulations revealed that splitting processing into separate streams for identifying and locating a shape led to better performance only under some circumstances. Provided that enough computational resources were available in both streams, split networks were able to develop more efficient internal representations, as revealed by detailed analyses of the patterns of weights between connections.

Elucidating dingo’s ecological roles: contributions from the Pelorus Island feral goat biocontrol project

2020 ◽  
Author(s):  
Benjamin L. Allen ◽  
Lee R. Allen ◽  
Michael Graham ◽  
Matt Buckman
Keyword(s):  
Native Vegetation ◽  
Apex Predators ◽  
Top Predators ◽  
Goat Population ◽  
Manipulative Experiments ◽  
Ecological Roles ◽  
Important Field ◽  
Small Livestock ◽  
Introduction Experiment ◽  
Feral Goat

ABSTRACT Understanding the ecological roles of apex predators remains an important field of study. The influence of apex predators on ecosystems can be either profound or negligible in different situations, and uncertainty still exists about the ecological roles of most top-predators, including Australian dingoes. This uncertainly is maintained by a dearth of experimental evidence investigating their roles. Such evidence is indispensable if dingo management is to be evidence-based. In this report, we discuss a recent experiment where dingoes were released on to an island as vertebrate biocontrol tools intended to eradicate feral goats and restore native vegetation being threatened by the goats. The experiment was successful, and the dingoes reduced the goat population to one or perhaps two male goats within ~2 years. This predator introduction experiment elucidated dingo’s effects on small livestock, their per capita predation rates, and their invasiveness or their ability to adapt and change their environment. The experiment confirmed that dingoes have the capacity to decimate populations of small livestock species and trigger a trophic cascade by reducing herbivory on vegetation. We encourage further manipulative experiments to explore the ubiquity of these results in different contexts.

scholarly journals Contributions of the early visual system to high-level visual distinctions

2021 ◽  
Vol 21 (9) ◽  
pp. 2412
Author(s):  
Lily E. Kramer ◽  
Talia Konkle ◽  
Marlene R. Cohen
Keyword(s):  
Visual System ◽  
Early Visual System ◽  
High Level

scholarly journals A dual role for shape skeletons in human vision: perceptual organization and object recognition

2019 ◽  
Author(s):  
Vladislav Ayzenberg ◽  
Frederik S. Kamps ◽  
Daniel D. Dilks ◽  
Stella F. Lourenco
Keyword(s):  
Object Recognition ◽  
Visual System ◽  
Perceptual Organization ◽  
Human Vision ◽  
Shape Information ◽  
Functional Roles ◽  
Response Profiles ◽  
High Level ◽  
Skeletal Model ◽  
Shape Skeletons

AbstractShape perception is crucial for object recognition. However, it remains unknown exactly how shape information is represented, and, consequently, used by the visual system. Here, we hypothesized that the visual system represents “shape skeletons” to both (1) perceptually organize contours and component parts into a shape percept, and (2) compare shapes to recognize objects. Using functional magnetic resonance imaging (fMRI) and representational similarity analysis (RSA), we found that a model of skeletal similarity explained significant unique variance in the response profiles of V3 and LO, regions known to be involved in perceptual organization and object recognition, respectively. Moreover, the skeletal model remained predictive in these regions even when controlling for other models of visual similarity that approximate low- to high-level visual features (i.e., Gabor-jet, GIST, HMAX, and AlexNet), and across different surface forms, a manipulation that altered object contours while preserving the underlying skeleton. Together, these findings shed light on the functional roles of shape skeletons in human vision, as well as the computational properties of V3 and LO.

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